Situation occur where bootloader cannot supply kernel with early

Situation occur where bootloader cannot supply kernel with early
random data. But a new source of entropy arrived a few months ago
-- KARL generates highly disturbed images for some kernels (well,
not for bsd.rd)
This assumes the tail of text (just before etext[]) is readable.
We are trying to use a portable symbol name, and also avoid reading
a locore0 which has been unmapped...
ok mortimer